1. Field of the Invention
The invention relates generally to controlled dispensing of fluids and more specifically to a method of controlling dispensing of fluids to a washing machine or the like.
2. Description of the Related Art
Chemical dispensers are commonly used in the commercial laundry industry to provide various chemicals to washing machines at the proper time in the cycle. Electrical signals from the washing machines (also later referred to as "washers") as provided in most washing machines are used to trigger delivery of alkalis, detergents, bleaches and other chemicals at particular points in the cycle to a particular machine. A number of problems confront commercial chemical delivery systems. First, the chemicals used are corrosive, viscous, and sometimes incompatible with one another. Controlling the exact amount of chemical dispensed, the order of chemical dispensing, and minimizing personnel and machine exposure to the concentrated liquids are all critical. Additionally, automated chemical delivery systems tend to minimize laundry personnel input in order to protect personnel and reduce human error. This practice, however, often results in empty chemical containers going unnoticed, which may cause a necessary chemical to be omitted from a wash cycle. Various systems have been used in the past to overcome the problems referred to above. U.S. Pat No. 4,964,185 teaches a system which uses solid chemicals that are sprayed with water to dissolve them. The system described in the '185 patent uses a feedback control system to compensate for the variable dissolving rate of such a solid and notifies the operator in the event of an outage of product. Water temperature, pressure and the condition of the solid product all impact the dissolving rate. The chemical delivery system disclosed in the '185 patent requires water temperature and pressure to be within limits that may not be available in every laundry. Not meeting these limit requirements would result in erratic and inaccurate delivery or chemical to the system washers. The system disclosed in the '185 patent also relies on electrical conductivity to determine the status of chemicals in the system. Therefore, electrically non conductive chemicals cannot be monitored by this system.
Dispensers that strictly use liquid chemicals have been devised, such as described in U.S. Pat. No. 5,014,211. The '211 patent system uses liquid chemicals with individual peristaltic pumps to deliver chemicals to a single delivery conduit that distributes product to various washers through valves and conductivity sensors. The '211 patent's reliance on conductivity sensors precludes complete monitoring of non-conductive chemicals.
U.S. Pat. No. 5,435,157 teaches the use of separate delivery conduits for incompatible chemicals in a dispenser that services two washers. While the '157 patent system solves some problems and minimize costs compared to single washer dispensers, there is no feedback to control the concentration or quantity of solution delivered to washers.
U.S. Pat. No. 5,059,954 discloses a chemical delivery system which monitors the level of chemicals in chemical containers. This system, however, requires use of a sensing device for each chemical container, and does not provide a method for automatically priming the chemical pumps, in order to keep the wash loads consistent.
It is therefore the object of this invention to provide a pressure sensor for each washer and a computer system incorporating means to detect the status of chemicals in each chemical container.
It is a further object of this invention to provide an automatic system that automatically primes the pump prior to dispensing chemicals to a washer.
Is also an object of the present invention to provide a system that significantly reduces the number of chemical and water sensing components required for a chemical delivery system.
It is furthermore an object of the present invention to provide a system that may be used not only for washers but also in the field of chemical manufacturing, medicine, and retail beverage services. It is therefore another objective of this invention to provide a method of sensing the status of chemicals in chemical containers and dispensing the chemicals from the containers.
It is therefore another object of this invention to provide a method of sensing the status of chemicals in chemical containers and dispensing the chemicals from the container.